Curitiba has a well planned and integrated transportation system, which includes dedicated lanes on major streets for a bus rapid transit system.[3][4] The buses are long, with 157 bi-articulated (split into three sections) and 29 single-articulated vehicles,[5] and stop at designated elevated tube-shaped stations to allow for fare prepayment and platform level boarding, complete with handicapped access. A small ramp folds down from the bus onto the platform so there is no gap to cross to enter or leave the vehicle. All door loading and fare prepayment allows for short dwell times in stations. 20% of the stations have passing lanes to allow for express services[6][7] The system, used by 85% of Curitiba's population (2.3 million passengers a day),[8][9] is the source of inspiration[10] for the TransMilenio in Bogotá, Colombia, Metrovia in Guayaquil, Ecuador as well as the Emerald Express (EmX) of Eugene, Oregon and Orange Line of the Los Angeles, California, The Strip and Downtown Express in Las Vegas, Nevada and for a future transportation system in Panama City, Panama, Transmetro system in Guatemala City, Guatemala, the Metrobús of Mexico City and Buenos Aires,[11] Argentina, and for the city of Bangalore.[12]

Recently, the transportation system has been facing problems due to the its reduced fleet and lack of maintenance. Buses represent only 1% of automobiles and overcrowding is a serious problem.[13] Curitiba is the Brazilian capital with the highest automobiles per inhabitants ratio, with 1.2 million vehicles for a population of 1.8 million inhabitants,[14] which explains the frequent traffic jams in the city.[15] The citizens are forced to find alternative ways of reaching their destinations, given that overcrowding prevents the users of boarding the buses.[16] For opponents of the government, the quality system has worsened since the last bid.[17] Bicycle riders are also forced to illegally use the dedicated lanes,[18] since Curitiba's accessibility to bicycle lanes is poor: Curitiba has just 35 km of exclusive bicycles lanes, much less many major European cities, such as Berlin, which contains 620 km of dedicated bicycle lanes.[19][20]

Curitiba has over one hundred years of history in public transportation. The first system was a tram pulled by a mule during the imperial time in 1887. From 1910, Curitiba grew faster, so in 1912 an electrical tram replaced the mule-tracked one.[21]

By the 1960s, Curitiba's population ballooned to 430,000, and some residents feared that the growth in population threatened to drastically change the character of the city. In 1964, Mayor Ivo Arzua solicited proposals for urban design. Architect Jaime Lerner, who later became mayor, led a team from the Universidade Federal do Paraná that suggested a reduction of private vehicle traffic in the downtown area and a convenient and affordable public transit system.[22] The plan also sought to concentrate development along the bus routes to maximise the benefit of the high capacity system.

This plan, known as the Curitiba Master Plan, was adopted in 1968. Lerner closed 15 November Street to vehicles, because it had very high pedestrian traffic. The plan had a new road design to minimise traffic: the Trinary Road System. This uses two one-way streets moving in opposite directions which surround a smaller, two-lane street where the express buses have their exclusive lane. This concept was first adopted in 1979, with the North-Side Trunk Line.[23]

Five of these roads form a star that converges to the city centre. Land farther from these roads is zoned for lower density developments, to reduce traffic away from the main roads. A number of areas subject to floods were condemned and became parks.[24]

In the 1980s, the Rede Integrada de Transporte was created, allowing transit between any point in the city by paying just one fare.[25]

Despite the success the system has been subject to criticism. Overcrowding is common at peak times and none of the routes extend beyond the municipal boundary of the city which forces passengers in the generally poorer outlying suburbs to have to change buses and pay two fares.[30] The system has also faced declining patronage and lost 14 million users between 2008 and 2014 while other Brazilian cities maintained or increased public transport usage.[31] Plans are underway to install an underground metro on claims the BRT cannot provide sufficient capacity.[32][33]

Express (Expresso Biarticulado): These are large high-capacity buses that have exclusive traffic lanes, spreading radially from the city centre in 5 directions. They are treated as an "above-ground subway" because of their speed, capacity and frequent service. They have bright red color schemes and operate with tubular shaped stations. Passengers pay to enter the stations. This allows very quick boarding and disembarking.

Inter-neighborhood (Interbairros): These are green buses that travel outside downtown. Lines 1 and 2 circle the city centre, the latter with a bigger radius. Lines 3 to 6 are important connections between some neighborhoods.

Direct lines (Linha Direta): Commonly called ônibus ligeirinho (quickie bus), these are silver buses designed to be the quickest links between two points. They cover large distances with few stops. They link with tube stations. Curitiba is the pioneer in the worldwide Rapid Bus development.

Feeder (Alimentador): These are local bus lines and are painted orange. All of them link one passenger terminal to a neighborhood and feed the express buses and other RIT lines with passengers. Large windows allow better sightseeing.

"Downtown Circulator" (Circular Centro): These small white buses are designed to circle the city centre, and are used by pedestrians as a quick way of getting to the other side of the area.

Regular routes (Convencional): These yellow-colored buses operate radially from the city centre.

Interhospitals (Interhospitais): These white buses circle the town and link the main city hospitals.

Tourism line (Linha Turismo): These colorful buses focus on the city's attractions. Paying R$35.00 / US$11.28 allows one to get on and off the bus five times, at the attraction of interest.

The environmental performance of alternative fuels are significant and contribute to improving air quality, especially in large cities of Brazil, where public transport systems are still largely made up of buses. These alternatives also produce social impact, since Brazil is a major producer of soybeans and ethanol, and the increased use of alternative fuels causes the generation of jobs, particularly in the field:[34]

^The plan is well documented and can be seen in the bus route map: [Image:Curitiba_PublicTransport.png|Bus route plan]

^One fare is confirmed by a US federal research stating that: "Passengers pay a single fare ... with unlimited transfers between buses". This may not be the same price to all passengers, as indicated by this CNN source, which claims the "system is subsidized by wealthy residents of the city center area", who perhaps pay more. In any case, all sources agree that payment for all transfers are done once for all daily rides, outside the stations, and prior to entering the bus.